Method of producing electromagnetic coils.



' Patented Dec. 28, 1915. 172 4.

C. H. THORDARSON.

METHOD OF PRODUCING ELECTROMAGNETIC COILS.

APPLICATION FILED 1 m. 11. 1915.

UNITED STATES PATENT OFFICE.

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, men or mnucnm nlqrnonanmc coma To all Y Be it known that I, Cnm'rznvH. Tnoa- DARSON, a citizen of the United States, and a resident ofChicago, inthe county of Cook and State of'Illinois, have inventedcertain new and useful Improvements in Methods of ProducinElectromagnetic Coils; and I do hereby eclare that the following is afull, clear, and exact description thereof, reference being had to theaccompanying drawings, and to the characters of reference markedthereon, which form a part of this specification.

This invention relates to a novel method of producing flat wireelectro-magnetic coilsor windings for transformers and otherelectro-magnetic devices, and the invention consists in the mattershereinafter set forth and more particularly pointed out in the appendedclaims.

An object of the invention is to reduce the cost of producin suchcoilsand to-reduee the dimensions 0 the coil produced as compared to itscapacit fol-work.

Another object o the invention is to provide an improved method ofproducing coils, whereby such coils may be made up of extremely thin andnarrow flat wires without involving complications in handling the wirein the difierent stages of the manufacture of the coil.

In producin a coil in accordance with my novel method apply to a sheetor web of electrically conductive metal of the required gage, and of asubstantial width to produce a number of flat wires, a thin insulatingcoating which, (for some metals may consist of an oxid formed on thesheet, and for others of an enamel applied thereto) thereafter slittingthe sai sheet into narrow strips of a width to produce the resultantflat wires; thereafter winding the flat wires thus produced into a coil,and thereafter treating or conditioning the end faces of the coil,formed by the edges ofthe flatwire, so as to remove or avoid sharpprojections or burs formed on said edges when cutting the sheet toproduce'the flat wires, and thereby avoiding short circuiting betweenthe turns. In some instances, the conditioning of the end faces of thecoil may be efiected by an acid of such character as to cut back intothe metal of the fiat wire at the exposed sides thereof, while beingneutral to the insulating covering, so as to leave, in effect, betweenthe turns overhanging insulating ledges con- Specification r Il'etteraIla tent Patented 28,1915. I a u auum uury nau. l mma-104.1

i of the edges of oxid or enamel In other 3 instances, the burs or,

roughened edges may be covered by an in-. 'sulati'ng' coatingto avoidshort circuitingquently passing the coatedsheet through an annealingchamber. la effect between lyticor enamel bath and a strip or sheet ofmetal to be coated, the insulatin tends to accumulate at the edges 0 thestrip or sheet so as to thereby substantially thicken the coated sheetor strip at its By reason of the capilthe liquid of the electrocoating.-may-be applied a the mar-l gins. For this reason it becomesimpractical to coat flat wires of the ultimate width required for thecoil inasmuch as the thickened margins prevent the flat wire being madeintocompactly and. symmetrically wound coils.

In the practice of my improved method for producing coils the edges ofthe coated sheet are sheared 01f at or before the time the sheet isbeing cut into'strips, so that the re portion of the sheet from-whichthe flat wires are cutis' of uniform gage throughout and may becompactlyand sym- I metrically wound into a coil. it is cially impossible,toapply such insulating coatmg to very thin and narrow stri s or wires,say of .0003 of an inch in thic ess and from i to of an inch inwidth,

reason of the mechanical difiiculties whic Furthermore,

are encounteredin passing such thin deli cafe strips through the coatingbath and winding them into a coil. This mechanical difliculty ofhandling the material is not encountered when the coil is produced by myimproved IDEthOdyfOI the reason that the sheet itself is of such widthas to be readily passed through the coating bath, and said sheet may bereadily. cut up into strips and the strips wound intocoils; However,regardless of the gage and width of the flat wire, the expense ofproducin same by my novel method is materially ret luced by reason ofthe greater facility of handling the material. n some instances I maywind the strips into coils directly from the cutquite impracticable, ifnot commerting machine, while in other cases I may Wind, the strips intorolls which are thereafter unrolled and wound into coils.

I have illustrated in the drawings the Various steps and stages of mynovel method.

In said drawings :-Figure'l illustrates a web or sheet which is firstsubjected to the coating bath and afterward cut to produce the fiat wireor strips] Fig. 2 is a perspective view of a coil, partially wound,produced from the flat wire cut from the sheet shown in Fig. 1. Fig. 3is an enlarged cross section of one of the coated fiat wires produced bymy novel method. Fig. 4 is a similar cross section of a coated flat wirewhich has been coated after being cut to its final width. Fig. 5 is anenlarged cross section of a number of turns of the coil before the endfaces thereof have been conditioned. Fig. 6 is asimilar view after theend faces have been. subjected to the conditioning process.

' The sheet 10, shown in Fig. 1, may be of any suitable width toproduce, when cut, a number of resultant fiat wires or strips 11. Afterthe sheet has been subjected to a coating bath to apply an insulatingcoating thereto the side edges 12, 12 which, as before stated, areslightly thicker than the remaining portions of the sheet are shearedoff.

Preferably, in the practice of my novel' method, the side edges of thesheet are,

. sheared off at the same time the sheet is cut or split into strips toform the. fiat wires. Thereafter the coated flat wire is wound toproduce the coil 13, shown in Fig. 2.

Fig. 3 shows a cross section of one of the flat wiresvll and also theinsulating coating 14 thereon. It will be noted that the thickness orgage of the flat Wire is uniform throughout the width of the wire. Incomparing the fiat wire 15 shown in Fig. 4 (which latter, it is assumed,has been coated as an individual wire) with the flat wire 11. shown inFig. 3, it will be notedthat in the former figure the coating solutionhas collected along the edges in a manner to produce on both sidesthereof thickened portions 16, substantially thicker than the body ofthe fiat wire, so that it becomes impracticable to compactly wind such awireinto a coil with all parts of the turns laid fiat upon each other,or to insure an assemblage of the flat wires in a coil with the edgesflush to produce smooth end faces, inasmuch as the thickened portionswill tend to cause the turns to slip or slide sidewise upon each otherand produce irregular or unsymmetrical coil end faces.

The fiat wires or strips may be cut from machine to the coil windingmachine, or they may be primarily formed into rolls and the rollsthereafter unwound and rewound into coils.

.ing sodium potassium tartrate, to form a thin oXid coating on thesurface of the sheet. Such an -o-xid coating may be produced extremelythin while possessing high insulating efficiency. For instance, whenemploying a flat wire of .0003 of an inch in thickness the coating oneach side need not exceed .0001 of an inch. It will thus be observedthat-the flat wire may be wound in a very compact coil or windingstructure so as to thereby reduce the dimensions of the coil, andalso-reduce its weight as compared to its electromagnetic efficiency.

When employing copper as a metal to'produce the flat wire I may coat thesheet with a suitable enamel having the required degree of thinness andat the same time possessing the required insulating efficiency.

After the coil has been wound, the end faces thereof present somewhatthe appearance illustrated in Fig. 5, with the edges of the fiat wireslightly roughened or burred due to the action of the cutting toolsthereon during the cutting operation. Such roughened. edges areobjectionable in the coil inasmuch as they form discharge points acrosswhich the turns of the coil are liable to short circuit. The endfaces ofthe coil may be conditioned to avoid such roughened edges of the flatwire either by coating the said faces with an insulating material tothereby insulate the turns from each other, or such conditioning may beeffected by means of an acid of such character that when applied to theend faces of the coil it acts to cut the side edges of the flat wireslightly back' from the planes of the said faces but which has no effecton the insulating coating. When using aluminum as the flat wirematerial, provided with an oxid insulating coating, I may treat-theedges of the wire to produce the result described by the use of asolution of diluted hydrocloric acid. After the edges of the wire havebeen thus treated the edges of the insulating coating, which have notbeen affected by the conditioning process, overhang the wire edges toproduce insulating ledges 17 which avoid short circuiting between theturns of the winding across said edges. Thereafter the end faces of-thecoils may be treated to a coat of thin insulating material, such asshellac, which may be applied by a brush or by dipping the coil in theshellac, or like solution.

When using copper wire coated with an insulating enamel I may employ forthe purpose of conditioning the end faces of the coil any suitable acidwhich will cut the copper but which is neutral to the enamel such, forinstance, as diluted nitric acid.

An advantage of the coil produced by my novel method in its use in atransformer, for instance, is that the edges of the flat wire may bevery efiiciently exposed to a circulating coating medium wherebyoverheating of the wire under heavy service is avoided.

I claim as my invention 1. The method of producing electro-magneticcoils, which consists in applying to a sheet of electrically conductivemetal an insulating coating, thereafter shearing the thickened edgesfrom the sheet and cutting the sheet into strips to produce flat wireconductors, and finally winding the flat wires thus produced into acoil.

2. The method. of producing electro-magnetic coils which consists inapplying to a sheet of electrically conductive metal an insulatingcoating, thereafter cutting the sheet into strips to produce fiat wireconductors, thereafter winding the flat wire thus produced into a coiland finally treating the end faces of the coil to insulate the windingturns from each other at said end faces.

3. The method of producing electro-magnetic coils which consists inpassing a sheet of electrically conductive metal through a bath to formthereon an insulating coating, shearing the thickened edges from saidsheet, and cutting said sheet into strips to produce flat wireconductors, winding the flat wire thus produced into a coil, and finallyconditioning the end faces of the coil to insulate the winding turnsfrom each other at said end faces.

4. The method of producing electro-magnetic coils which consists intreating a sheet of electrically conductive metal to form thereon aninsulating coating, cutting said sheet into strips to produce flat wireconductors, winding the flat wire thus produced into a coil and treatingthe edges of the flat Wire at the end faces of the coil to remove thebur therefrom while retaining the coating to form insulating ledgeswhich overhang the edges of the wire.

5. The method of producing electro-magnetic coils which consists intreating a sheet of electrically conductive metal to form thereon aninsulating coating, cutting said sheet into strips to produce fiat wireconductors, winding the flat wire thus produced into a coil, treatingthe edges of the Hat wire at the end faces of the coil to remove the burtherefrom, while retaining the coating to form insulating ledges whichoverhang the edges of the wire, and finally coating the end faces of thecoil with a thin insulating material.

6. The method of producing electro-magnetic coils which consists inapplying to both sides of a very thin, wide sheet of electricallyconductive metal an insulating coating, thereafter cutting the sheetinto narrow strips to produce flat wire conductors covered on both sideswith an insulating coating and finally winding the flat insulated wiresinto a coil.

In testimony that I claim the foregoing as my invention I affix mysignature in the presence of two witnesses, this 29th day of December,A. D. 1914.

CHESTER THORDARSON.

Witnesses:

W. L. HALL, G. E. DOWLE.

